Rotary-impact drill



AU8- 13, 1968 J, K4 MENTON 3,396,807

ROTARY- IMPACT DRILL Aug. 13, 1968 1. K. MENTON ROTARY-IMPACT DRILL 2 Sheets-Sheet 2 Filed Sept. 27, 1966 Z f M V/ .M V N \v\ 1 @y Y A77' rae/vans' United States Patent O 3,396,807 ROTARY-IMPACT DRILL Jack K. Menton, 11191 Saratoga Drive, Los Alamitos, Calif. 90720 Filed Sept. 27, 1966, Ser. No. 582,405 8 Claims. (Cl. 175-293) The present invention relates to earth boring equipment such as commonly used in drilling oil wells, and, more particularly, to an improved rotary-impact drill.

Generally speaking, a rotary-impact drill is an earth boring drill which is adapted to deliver impacts to its drill bit while the latter is being rotated. To accomplish this, it is common for rotary-impact drills to include an anvil and a hammer spring biased toward each other. The anvil is connected to the drill bit for the rotaryimpact drill, while a hammer is mounted above the anvil for axial movement relative to and for rotation with a rotary drive member such as a drive shaft. Complementary, tooth-shaped hammer and anvil cams are carried on the top and bottom of the anvil and hammer, respectively. The cams are shaped such that as the hammer turns relative to the anvil and earth boring drill bit, the hammer cams ride up along sloping surfaces of the anvil cams and upon reaching shoulders on the cams, drop heavily onto the anvil. -In this manner, the vertical drop of the hammer onto the anvil imparts simultaneous vertical and rotational impulses to the drill bit as it bores into the earth.

In theory, all conventional rotary-impact drills operate on the principle just described. Unfortunately, however, presently available rotary-impact drills fall far short of their maximum theoretical efiiciency and are subject to numerous practical problems. For example, conventional rotary-impact drills do not develop either maximum rotational or vertical impacts upon hammer drop. One cause for the less than maximum vertical impact is the fact that the hammer drop is not vertical. Rather, it is at a downward angle. This means (l) that the hammer cams strike the mid-portions rather than the lower base portions of the sloping anvil cams, (2) that the hammer does not travel through its maximum stroke prior to striking the anvil, and (3) that the ham-mer therefore does not reach a maximum downward velocity prior to impact. By the same token, since the hammer cams strike the anvil cams at an angle, the rotational impact is less than would be developed if there were horizontal impact relative to the vertical axis of the drive shaft or the hammer.

In addition to the foregoing shortcomings, the efficiency of conventional rotary-impact drill operation is materially affected by sand and water seeping into and around the working parts in the drill. In particular, sand tends to work its way around the rotating drive shaft and into the area of seals between the drive shaft and the casing surrounding the workings of the drill. The sand quickly damages the seals which therefore require periodic servicing and replacement. Upon passing the seals, the sand materially impairs the operation of the drill.

Also, in rotary-impact drills, it is common that the casing surrounding the workings of the drill define a closed chamber for receiving oil. Unfortunately, in some drills the inner volume of the oil chamber changes due to the telescopic action of the drill during drilling operations to effect a pumping action which draws water and debris into the chamber to further impair efficient drill operation.

Furthermore, a rotary-impact drill should work equally well in tension or compression. If a drill with this ability became stuck, it could easily drill its way upward out of the drill hole in response to an upward pull. Presently available rotary-impact drills do not possess this feature.

'In view of the foregoing problems, it is a general object of the present invention to provide an improved rotaryimpact drill which is capable of developing separate, maxi- :mum rot-ational and vertical impacts and thereby provide improved drilling results.

Another object of the present invention is to provide an improved rotary-impact drill in which the workings of the drill are sealed from water and debris.

A further object of the present invention is to provide an improved rotary-impact drill including means for trapping sand and other debris and preventing same from damaging seals in the drill.

Still another object of the present invention is to provide an improved rotary-impact drill wherein the oil chamber within the drill structure has a constant volume and does not pump water and debris into the chamber during drill operation.

A still further object of the present invention is to provide a rotary-impact drill which will operate equally well in tension and compression at maximum efliciency.

The foregoing as well as other objects and -advantages of the present invention may be more clearly understood by reference to the following detailed description when considered with the drawings which, by way of example only, illustrate a preferred form of the rotary-impact drill of the present invention.

In the drawings:

FIGURE 1 is a side view of the rotary-impact drill, partially in section, illustrating the drill boring a hole within the earth;

FIGURE 2 is a sectional view taken along the line 2-2 in FIGURE 1 showing the inner workings and construction of the rotary-impact drill;

FIGURE 3 is a fragmentary sectional view of the lower portion of the rotary-impact drill illustrating its anvil and hammer cam arrangement with the hammer cams riding upward along the sloping surfaces of the anvil cams;

FIGURE 4 is a fragmentary sectional view of the hammer and anvil cam portion-s of the rotary-impact drill illustrating the positions of the cams just prior to vertical drop of the hammer onto the anvil;

FIGURE 5 is a sectional view taken along the line SWS in FIGURE 3;

FIGURE 6 is a sectional view taken along the line y6 6 in FIGURE 4;

FIGURE 7 is a fragmentary sectional view taken along the line 7--7 in FIGURE 5; and

FIGURE 8 is a fragmentary sectional view taken along the line 8-8 in FIGURE 6.

In the drawings, the rotary-impact drill is represented by the numeral 10 and generally speaking includes an anvil 12 and a hammer 14. The anvil 12 is connected to and carries a drill bit for the rotary-impact drill 10, while the hammer 14 is mounted for axial movement above and for rotational movement relative to the anvil, and is continuously urged downward toward the anvil by a coil spring 18. The lower and upper surfaces of the hammer 14 and the anvil 12 carry complementary, toothshaped hammer and anvil cams 20 and 22 including cooperating vertically sloping surfaces 24 terminating in substantially vertical shoulders 26. The hammer and anvil, as Well as the hammer cams and anvil cams, are arranged relative to each other such that as the hammer 14 rotates relative to the anvil 12, the hammer cams 20 repeatedly ride up along the sloping surfaces 24 of the anvil cams and under the influence of the coil spring 18 drop heavily onto the anvil cams upon leaving the sloping surfaces and reaching the shoulders of the anvil cams.

The foregoing structural arrangement is somewhat similar to conventional rotary-impact drills. From this point on, however, the present invention differs substantially and in extremely important respects from conventional drills by the inclusion of cooperative means represented generally by the numeral 28. The cooperative means 28 are connected to the anvil 12 and to the hammer 14 and are adapted to direct the hammer cams 2t? vertically downward during each drop with the shoulders 26 of the hammer cams dropping along and immediately adjacent the shoulders 26 on the anvil cams. This insures a maximum hammer stroke prior to striking the anvil. It also insures that the hammer 14, under the influence of the coil spring 1S, reaches a maximum velocity prior to impact with the anvil 12 and hence insures a maximum hammer and anvil vertical impact for each hammer drop. The cooperative means 28 are also designed to impart a maximum rotational impact to the anvil 12 and drill bit 16 just prior to each drop of the hammer 14.

Accordingly, in the rotary-impact drill 10, the drill bit 16 is repeatedly subjected to a maximum rotational impulse followed immediately by a maximum vertical impulse. The resulting drilling action has proven to be vastly superior to conventional rotary-impact drills employing simultaneous vertical and rotary impulses of lesser magnitude.

More particularly, as illustrated most clearly in FIG- URES l and 2, the rotary drive for the hammer 14 and hence for the anvil 12 and drill bit 16 is through a tubular drive shaft 30. In this regard, the upper end of the drive shaft 30 is threadedly connected to the lower end of a tubular box member 32 which in turn is threadedly connected to a tubular pin 34 extending from the bottom of a drill collar 36.

The drive shaft 30 extends downwardly from the box member 32 through a tubular cover member 38 and the hammer 14 and anvil 12 housed therein and terminates inside a crossover sub 4t) connecting the drill bit 16 to the anvil. At its lower end, chevron seals 42 extend around the drive shaft 30 and tightly against the inside of the sub 40 to isolate the inside of the cover member and the workings of the drill 10 from the end of the drive shaft. The seals 42 are held in place by upper and lower retaining nuts 44 and 46 on the threaded lower end of the drive shaft 30.

Thus arranged, the lower end of the drive shaft 30 opens into a chamber 48 in the upper end of the drill bit 16. Side ports S extend from the lower end of the chamber to the cutting face of the drill bit 16. Accordingly, a straight, unbroken circulation path is provided completely through the drill and allows fluid or air to be circulated in either direction through the drive shaft without fear of contaminating the workings of 4the drill sealed within the cover member 38.

As indicated most clearly in FIGURE 2, the anvil 12 is of a tubular design having a central opening 52 for axially receiving the drive shaft 3G, The inner lower end of the anvil is threaded and is connected to the sub securing the drill bit 16 to the anvil while the upper surface of the anvil includes the previously described anvil cams 22 which extend around the central opening 52.

Within the anvil 12 and below the cams 22, the central opening 52 is of enlarged radial dimension and houses a roller bearing unit 54, upper and lower thrust bearing units 56 and 58 and a coil spring 60. The bearings of the roller bearing unit 54 engage and roll around the outer surface of the drive shaft to support the anvil for rotary movement around and relative to the drive shaft.

In drilling operations, upper thrust bearing unit 56 is forced against the bottom of an annular shoulder 62 on the drive shaft 30 while the lower thrust bearing unit 58 is forced against the top of the sub 40 by the coil spring which extends around the drive shaft. In this arrangement, the coil spring 60 transmits the weight of the drive shaft 30 and any axial forces thereon to the drill bit 16 through the sub 40. The coil spring 60 also cushions the drive shaft against rebound of the drill bit and anvil after vertical impact of the hammer 14. The design also allows the hammer 14 to work equally well should the drill bit 16 become stuck and upward pull on the drive shaft 36 be required during drilling operation. In particular, an upward pull on the drive shaft 30 causes the drive shaft to move upwardly relative to the hammer 14 until the nut 44 engages the bottom of the thrust bearing unit S8. Thereafter, the upward pull on the drive shaft 30 compresses the spring 60 and forces the thrust bearing unit 56 upward against an annular shoulder 63 on the anvil 12. The continued upward pull then forces the anvil 12 and drill 19 upwardly as the drill bit 16 drills its way out of the drill hole in response to the rotary and vertical impulses applied thereto.

The upper, outer portion of the anvil 12 is threaded and tightly mates with the internally threaded lower end of the tubular cover member 38. Thus connected, the cover member 38 extends vertically from the anvil and i-s adapted to axially receive the hammer 14, the drive shaft 30, and the coil spring 18 which extends around the drive shaft aoove the hammer.

The upper end of the cover member 38 is closed by a retainer nut 64. The nut 64 extends around and axially receives the drive shaft 30. Also, the nut houses a sand trap 66, a seal unit 68 and a pair of roller bearing units 70 and 72.

With respect to the sand trap 66, it comprises an annular recess 74 on the inside of the nut 64 around the central opening receiving the drive shaft 30. The recess 74 is generally of an annular, frusto-conical shape having outwardly projecting lower annular pocket 76. Set screw covered side ports 78 extend from the outside of the nut 64 to the recess to provide means for depositing oil within the trap and upper and lower wiper rings 80 and 82 are seated in the inner surface of the nut above and below the recess to provide means for wiping the outer surface of the drive shaft as it is telescoped relative to the cover member 38.

In operation, any sand seeping around the outside of the drive shaft 30 and into the top of the nut 64 enters the top of the recess 74. As the drive shaft 30 turns and as the cover member 38 rotates relative to the drive shaft, the sand is thrown outwardly and travels down along the sloping inner surfaces of the recess into the pocket 76. The sand is thus trapped in the pocket and prevented from travelling further along the drive shaft into the area of the seal unit 68. In the latter respect, the seal unit 68 comprises chevron seals 84 extending tightly around the drive shaft and seated within the retainer nut 64 lbelow the sand trap 66. Since sand is prevented from working its way into the chevron seals 84, they have a much longer useful life than in conventional rotary-impact drills and provide eicient sealing between the drive shaft 30 and the cover member 38 over long periods of drill operation.

With regard to the upper and lower roller bearing units 70 and 72, they are seated within the nut 64 with their bearing around and engaging the `outer surface of the drive shaft 30 to support the nut and cover member 38 for rotation around the drive shaft. The roller bearing units are retained within the lower end of the retainer nut 64 by a thrust bearing unit 86 which engages the lower end of the retainer nut and the bottom of the lower roller bearing unit. The thrust bearing unit 86 is in turn continuously urged upward against the bottom of the retainer nut 64 by the coil spring 18 which also continuously bears downward on the top of the hammer 14.

As most clearly illustrated in FIGURES 2 and 5, the hammer 14 is of tubular construction for receiving the drive shaft 30 and carries the hammer cams 20 on its lower surface. The hammer 14 is also mounted for axial movement along as well as rotary movement with the drive shaft 30. To accomplish this, the inner surface of the hammer 14 includes four equally spaced radially extend- 1ng keyways 88 for receiving keys 90 extending radially from the outer surface of the drive shaft 30. The keys 90 ride axially along the keyways 88 to permit the hammer 14 to move vertically along the drive shaft. The keys, however, engage the sides of the keyways to lock the hammer for rotation with the drive shaft, while the coil spring 18 continuously urges the hammer downward against the top of the anvil 12. Accordingly, as the drive shaft 30 rotates, it produces a like turning of the hammer 14. When the drill bit 16 is turning in relatively soft earth such as sand, the hammer cams 20 remain locked to the anvil cams 22 and the rotation of the hammer produces a like rotation of the anvil and drill bit. However, as the drill bit bores into more solid earth, the drill bit tends to stick therein and the hammer cams tend to rotate relative to the anvil cams with the foregoing rotational and vertical impacts imparted to the drill bit under the control of the previously referred to cooperative means 28.

More particularly, as illustrated most clearly in FIG- URES 3-8, the cooperative means 28 includes a plurality of shoulders 92, one for each anvil cam 22. The shoulders 92 include inclined lower surfaces, are equally spaced from each other, radially spaced from the hammer 14, and are connected to and extend inwardly from the inner surface of the cover member 38 above the upper surface of the anvil cams 22. Since the shoulders 92 are connected to and extend from the cover member 38, they are ixedly located relative to the anvil cams and rotate therewith.

In addition to the shoulders 92, the cooperative means 28 includes a plurality of lugs 94, one for each shoulder. The lugs 94 include inclined top surfaces complementary to the lower surfaces of the shoulders 92, are spaced equally from each other, and extend radially outward from the lower end of the hammer 14 adjacent the hammer cams 20. Thus positioned, .the lugs 94 are adapted to only strike vertical sides of the shoulders 92 when the hammer cams move vertically to the top of and off the anvil cams. In this respect, the shoulders 92 and lugs 94 are spaced relative to each other and to the anvil and hammer cams such that the lugs only strike the shoulders and impart rotary impulses to the anvil 12 when the hammer cams are moving in a horizontal plane with a maximum annular velocity, that is when they have just left the sloping surfaces of the anvil cams and when the anvil and hammer cam shoulders are in substantial vertical alignment (see FIGURES 6 and 8).

Accordingly, with the illustrated arrangement of the shoulders 92 and lugs 94, maximum rotary impulses are impar-ted to the anvil 12 and hence to the drill bit 16 each time the hammer cams 20 ride completely up the sloping surf-aces 24 of the anvil cams 22 and just prior to the vertical drop of the hammer 14 onto the anvil. In this respect, the vertical sides of the shoulders 92 act to direct the hammer 14 in a vertical direction downward against the anvil 12 during the drop of the hammer. In particular, as the hammer 14 drops onto the anvil 12, the shoulders 26 of the anvil and hammer cams pass immediately adjacent each other to insure the maximum stroke for the hammer during each drop. Since the hammer travels through a maximum distance before striking the anvil, the coil spring 18 imparts a maximum downward velocity to the hammer prior to impact. Accordingly, the hammer 14 contacts the anvil 12 with a maximum momentum to impart a maXimum vertical impulse to the anvil and the drill bit 16.

In the foregoing manner, when the drill bit 16 is stuck in or its rotation retarded by relatively firm soil, the hammer 14 repeatedly imparts rotational impulses to the drill bit 16 each followed 'by a grnaximum vertical impulse to free the bit and cause it to rotate and bore into the soil.

As previously indicated, the hammer 14, anvil 12 and spring members 18 comprise the workings of the rotaryimpact drill and are sealed within the cover member 38. In particular, the workings are sealed and operate within -an oil chamber 96 defined by the cover member 38 and the upper and lower chevron seals 84 and 42 around the drive shaft 30. The chamber is adapted to be oil filled through set screw covered side ports 98- located immediately below the upper chevrons 84. In the illustrated form of the present invention, the outer diameter of the upper portion of the shaft 30 is equal to the outer diameter of the seals 42. Therefore, the oil chamber 96 maintains a constant volume during operation of the rotary-impact drill. Accordingly, there is no pumping action of liuid within the cover member 38 and water and debris is not drawn into the oil chamber during drilling operations.

From the foregoing, it is appreciated that the present invention provides an improved rotary-impact drill which develops separate maximum rotational and vertical impacts on a drill bit while the bit is boring into the earth. The rotary-impact drill also is constructed such that its workings operate within the sealed container free from sand, debris or water which would otherwise impair its e'licient operation.

While a particular form of rotary-impact drill has been described in some detail herein, changes and modifications may be made in the illustrated form without departing from the spirit of the invention. It is therefore intended that the present invention `be limited in scope only by the terms of the following claims.

I claim:

1. A rotary-impact drill, comprising:

an anvil adapted for connection to Ia drill bit for turning therewith;

la hammer mounted for axial and rotational movement relative to said anvil;

spring means continuously urging said hammer toward said anvil;

complementary, tooth-shaped hammer and anvil cams on said hammer and anvil, respectively, including cooperative vertically sloping surf-aces terminating in su-bstantially vertical shoulders whereby as said hammer rotates relative to said anvil, said hammer cams repeatedly ride up along said `sloping surfaces said zanvil cams .and under the inuence of said spring means drop heavily onto said Vanvil cams upon leaving said ysloping surfaces and reaching rsaid shoulders of said anvil cams;

and cooperative means connected -to said anvil and hammer for directing said hammer cams vertically downward during ecah drop with said shoulders of said hammer cams dropping along and immediately adjacent said shoulders of said .anvil cams to insure a maximum hammer stroke and a maximum hammer and yanvil impact during each drop.

2. The combination of claim 1 wherein said cooperative means are further adapted to impart rotational impulses to said anvil and drill bit just prior to each drop of said hammer.

3. The combination of claim 2 wherein said cooperative means includes:

a plurality of shoulder means, one for each anvil cam, said shoulder means being equally spaced from each other, radially spaced from said hammer and connected to said anvil above said anvil cams to turn therewith;

a plurality of lugs, one for each shoulder means, said lugs being spaced equally from each other and eX- tending radially from said hammer to strike said shoulder means when said hammer cams move otf said anvil cams sloping surfaces and above said anvil cams;

and said shoulder means and lugs being spaced relative to each other and to said anvil and hammer cams such that said lugs strike said shoulder means and impart rotational impulses to said anvil when said hammer cams are rotating at a maximum angular velocity and leave said sloping surfaces of said anvil cams and said anvil and hammer cams shoulders are in substantial vertical alignment, and such that said shoulder means then direct said hammer cams -downward to impact with said anvil cams, corresponding ones of said cam shoulders passing 'immediately adjacent each other to insure a maximum hammer stroke yand a maximum hammer and anvil impact upon each hammer drop.

4. The combination yof cl-aim 2 further includ-ing:

vertical drive shaft means for turning about its longi` tudinal axis;

means mounting said hammer for axial movement along and rotational movement with said drive shaft;

means mounting said anvil for rotation relative to said drive shaft;

and second spring means between said drive shaft and said drill bit carried by said anvil for carrying and transmitting the weight of said drive shaft and axial forces thereon to said drill bit.

5. The combination of claim 2 further including:

-a vertical drive shaft for turning about its longitudinal axis;

means mounting said hammer for axial movement along and rotational movement with said drive shaft;

means mounting said anvil for rotation `relative to said drive shaft;

a tubular cover means closed at its lower end by and connected to said anvil for axially receiving said hammer;

first sealing means between said drive shaft and said cover means above said hammer;

and second sealing means between said drive shaft and said anvil defining a closed constant volume oil chamber within said cover means housing said hammer, anvil and spring means.

6. The combination of claim 5 further including a sand trap above said lirst seal means including an annular recess in said cover means open to said drive shaft, said recess including a lower, outer, annular pocket for receiving sand and the like which seeps around said drive shaft and into said cover means and which is thrown outward upon a turning of said cover means and said drive shaft.

7. The combination of claim 5 wherein said drive shaft is tubular and provides a flow path for high pressure fluid downward through ports in said drill bit.

8. The combination of claim 5 wherein said spring means is stationed within said chamber above said hammer and bears downward on a top surface of said hammer and upward on said cover means around said drive shaft, and wherein said combination further includes second spring means in said chamber below said anvil cams, said second spring means bearing downward on said drill bit carried by the bottom of said anvil and upward on said drive shaft during downward drilling and upward on said anvil when said drive shaft is pulled upward to work said bit from its drill hole whereby said second spring means carries and transmits the weight of said drive shaft vand axial forces thereon to said drill bit during downward drilling and transmits tension pull on drive shaft to anvil as said drill bit is worked upward in said drill hole.

References Cited UNITED STATES PATENTS 1,845,074 2/1932 Billstrom 175-298 1,901,513 3/1933 Harris 175-298 2,054,255 9/1936 Howard 175-298 2,307,927 1/1943 Hamon 175-298 2,613,917 10/1952 Postlewaite 175-298 X CHARLES E. OCONNELL, Primary Examiner'.

R. E. FAVREAU, Assistant Examiner. 

1. A ROTARY-IMPACT DRILL, COMPRISING: AN ANVIL ADAPTED FOR CONNECTION TO A DRILL BIT FOR TURNING THEREWITH; A HAMMER MOUNTED FOR AXIAL AND ROTATIONAL MOVEMENT RELATIVE TO SAID ANVIL; SPRING MEANS CONTINUOUSLY URGING SAID HAMMER TOWARD SAID ANVIL; COMPLEMENTARY, TOOTH-SHAPED HAMMER AND ANVIL CAMS ON SAID HAMMER AND ANVIL, RESPECTIVELY, INCLUDING COOPERATIVE VERTICALLY SLOPING SURFACES TERMINATING IN SUBSTANTIALLY VERTICAL SHOULDERS WHEREBY AS SAID HAMMER ROTATES RELATIVE TO SAID ANVIL, SAID HAMMER CAMS REPEATEDLY RIDE UP ALONG SAID SLOPING SURFACES SAID ANVIL CAMS AND UNDER THE INFLUENCE OF SAID SPRING MEANS DROP HEAVILY ONTO SAID ANVIL CAM UPON LEAVING SAID SLOPING SURFACES AND REACHING SAID SHOULDERS OF SAID ANVIL CAMS; AND COOPERATIVE MEANS CONNECTED TO SAID ANVIL AND HAMMER FOR DIRECTING SAID HAMMER CAMS VERTICALLY DOWNWARD DURING EACH DROP WITH SAID SHOULDERS OF SAID HAMMER CAMS DROPPING ALONG AND IMMEDIATELY ADJACENT SAID SHOULDERS OF SAID ANVIL CAMS TO INSURE A MAXIMUM HAMMER STROKE AND A MAXIMUM HAMMER AND ANVIL IMPACT DURING EACH DROP. 